JON Venables and Robert Thompson, both aged 11, became the youngest convicted murderers in Britain for almost 250 years when a jury at Preston crown court found them guilty yesterday of abducting and murdering two-year-old James Bulger.

They were sentenced to be detained at Her Majesty's pleasure and were expected to be kept locked up for at least 20 years.

Mr Justice Morland described the abduction and murder of James on the railway track at Walton, Merseyside, as a cunning and wicked act of 'unparalleled evil and barbarity'.

After the boys had been taken down from the dock, the judge made a strong statement attacking the influence of violent films on children. 'It is not for me to pass judgment on their upbringing, but I suspect exposure to violent video films may in part be an explanation.'

Later, the Home Secretary, Michael Howard, said he was horrified by events that led up to James's death. The boys would be held in separate secure units until a sentence plan was drawn up involving their placement in secure accommodation, he added.

Court No 1 was hushed as the jury delivered its verdicts on Thompson, known as Child A before reporting restrictions were lifted, and Venables, known as Child B. It returned at 5.15pm after five and a half hours of deliberation. As the foreman said 'guilty' to the count of murder, Susan Venables, Jon's mother, cried and his father, Neil, buried his head in his hands. Jon looked at the jury wide-eyed while Robert Thompson sat impassively. His mother, Anne, was not in court.

James Bulger's parents, Ralph and Denise, who is heavily pregnant, were both in the public gallery. As it was read, Denise was kissed by Detective Superintendent Albert Kirby, who led a force of up to 200 police officers in the investigation.

The judge ordered the nine men and three women of the jury to deliberate for a further half hour as it was unable to reach a unanimous verdict on the charge of attempted abduction of another two-year-old. When the two boys returned to the dock at 5.45pm Venables was crying inconsolably.

His solicitor, Lawrence Lee, said later that he had broken down after the murder verdict and said: 'Would you please tell them I'm sorry.'

Eight members of the Bulger family were present. One shouted as the boys left the dock: 'How do you feel now you little bastards?'

Detectives who interviewed the boys said after the trial that the two were evil and fixated on killing. Sergeant Phil Roberts said: 'These two were freaks who just found each other. You should not compare these two boys with other boys - they were evil. The other kick was fooling the public and the police.'

Mr Justice Morland said they would remain in custody for 'many, many years' until the Home Secretary was satisfied they were no longer a danger.

The boys will be returned to the separate local authority secure accommodation in which they have been held since they were arrested in February. At 15 they may be moved into a young offenders institution, and from 21 into adult prisons.

The jury failed to reach a verdict on the attempted abduction charge, which the judge ordered to lie on file, and was discharged.

After the case, Detective Superintendent Albert Kirby said he had seen no evidence to suggest that the boys had access to videos any worse than might be found in many households. As to what had driven the two schoolboys to kill he said: 'The answer to that will probably not be known for some time.'

Outside the court, a crowd of about 200 people had gathered by 6.20pm when separate police vans drove Thompson and Venables away. There were shouts of 'kill them' and 'hang them' but no violence.

The Bulger trial lasted 17 days, 13 dedicated to examining the movements of Thompson and Venables as they walked James from Bootle shopping centre for more than two miles to the scene of his death in Walton. The defence offered no evidence.

The only mitigation offered was a reminder from Brian Walsh, QC, acting for Venables, that the boy had shown remorse as he confessed to killing James. 'What about his Mum? Tell her I am sorry,' he had said.